} Y input O, feet between external have zero circuit, by adjusting potentiometer allows 50kn potential than O foot foot high Uy, the modulation signal u ( ) is superimposed with the DC input voltage UY Y channel. Adjust the potentiometer to change the modulation index Ma. Output terminal, feet to bandpass filter tuned to the carrier frequency., feet between the outer negative feedback resistor connected to the Y channel. The circuit shown indiscriminately 21-39 double-sideband amplitude modulation circuit can be composed, adjust the potentiometer is intended to make the Y channel O, feet between the DC potential difference is zero, the Y-channel input signal only the AC modulation signal. In order to reduce the current flowing through the potentiometer, accurate and easy to zero, can increase two 75051 resistor, such as increased each lOkn.